Added support for postgresql database
Updated Gemfile to decide which database driver to install
Merge pull request #27 from mfojtik/db_support

Add support for postgresql cartridge
Updated README.md for the postgresql support
Merge pull request #28 from mfojtik/readme

Update README.md for the postgresql support
Quote parameters which are potentially numeric
Merge pull request #29 from BanzaiMan/bz970150

Quote parameters which are potentially numeric
Fix broken installation when there is no support for set_env_var()
Merge pull request #30 from mfojtik/ose

Fix broken installation when there is no support for set_env_var()